Oil circuit interrupter



M BY

w i] TORN E R. E. FRIEDRICH 2,547,202

OIL CIRCUIT INTERRUPTER April 3, 1951 Filed Sept. 27, 1947 2Sheets-Sheet 1 fly].

. INVENTOR wnwzsszs;

fofierz E Friedrich.

W/EM

April 1951 R. E. FRIEDRICH 2,547,202

OIL CIRCUIT INTERRUPTER Filed Sept. 27, 1947 2 Sheets-Sheet 2 WITNESSES:INVENTOR WW W Patented Apr. 3, 1951 2,541,202 7 on. orncorr INTERRUPTERRobert E. Friedrich, Pittsburgh, Pa,

assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application September 2?, 1947, Serial No.776,569

6 Claims. 1

This invention relates to circuit interruptcrs in general, and moreparticularly, to arc-extinguishing structures and operating mechanismstherefor.

A- general object of my invention is to provide an improved circuitinterrupter in which an im proved hydraulic operating mechanism isprovided to effect operation of the contact structure.

Another object is to provide an improved arcextinguishing unit in whichthe contact structure is hydraulically operated and which is providedwith venting means to vent the unit fol lowing circuit interruption,which venting means is actuated by-the improved hydraulic operatingmechanism.

Still another object is to provide an improved circuit interrupter ofthe type establishing both a pressure-generating :arc and aninterrupting arc with fluid passage means interconnecting the two arcs.In my invention, I provide a separate fluid moving means to .assist inlow current i..-- terruption and I provide a separate passageinterconnecting the fiuid moving means with the interrupting arc toprevent contamination of the fluid sent by the fluid moving means towardthe interrupting are.

A further object is to provide an improved arcextinguishing unit withventing means at op posite ends thereof to provide a chimney ventingeffect, and to provide hydraulic means which not only efiects separationof the contact structure associated with the unit but also effectsopening of the venting means following interruption of the circuit.

Another object is to provide an improved hydraulic operating mechanismfor the contact means of a circuit interrupter in which the constructionis such as to minimize hydraulic friction losses.

Still a further object is to provide improved circuit interrupter of thetype specified in the immediately preceding paragraph in which aseparate delayed acting low current piston is incorporated which isactuated following a predetermined opening movement of the hydraulicoperating mechanism.

Further objects and advantages will readily be come apparent uponreading the following specification taken in conjunction with the ings,in which:

Figure l is a side elevational view, partly in section, of an improvedcircuit interrupter enebodying my invention and shown in the closedcircuit position;

. closed circuit position;

Fig.3 is a view taken at right angles to that of Fig. 2 with the contactstructure shown in the partially open circuit position, and

Fig. 4 is an enlarged fragmentary view taken substantially along theline IVIV of Fig. 3.

Referring to the drawings, and more particularly, to Fig. 1 thereof, thereference numeral I designates a tank filled to the level 2 with asuitable arc-extinguishing fluid 3, in this instance circuit breakeroil. Depending from the cover 4 of the tank I are a pair of terminalbushings 5 which support at their lower ends arcextinguishing units,generally designated by the reference character 6.

The arc-extinguishing units 6 are electrically interconnected in theclosed circuit position, as shown in Fig. l, by a bridging member Ireciprocally operated in a vertical direction by an insulating lift rod8. The lift rod 8 may be actuated in a vertical direction by suitablemechanism, not shown, which is responsive to either manual operation orto the existence of excessive current conditions in the protectedcircuit.

Referring to Fig. 2, which more clearly shows the internal constructionof the arc-extinguishing units it will be noted that a conducting contact foot 9 is threadedly secured and clamped to the lower end of theterminal stud, not shown, which extends interiorly through the terminalbushing 5. integrally formed with the contact foot 9 is the top metallicplate H] of the unit 5. The plate Ill in conjunction with insulating tierods, not shown, fixedly supports in place a plurality of insulatingplates, more fully described hereinafter and defining a relativelyvented interrupting chamber, generally designated by the referencenumeral H. A stationary contact !3 cooperates with a movable contact Mto establish an interrupting are 55 within the inter rupting chamber II,as more clearly shown in Fig. 3. Rigidly secured to the'lower end of themovable contact M is an insulating rod 16, the lower end of which isfixedly secured to another movable contact member I! which makesengagement in the closed circuit position, as shown in with relativelystationary pressuregen crating contacts 18.

The stationary contacts [3 are electrically con nected by a verticalspider construction IS with relatively stationary contacts 29', thelatter bearing against the external surface of the movable callyextending passages 28 contact [4 during the downward opening move mentthereof.

The electrical connection between the station-- ary contacts i3, 28 maybe effected by strap connectors 2f, the latter being brazed to the outersurfaces of the contacts I8, 20. Preferably, the contacts i8, 25 arepivotally mounted by pins 22 and biased inwardly toward the movablecontact structure by torsion springs 23.

The movable pressure-generating contact member ll separates from thestationary pres" sure-generating contacts l8 to establish apressure-generating are 26 within a relatively confinedpressure-generating chamber, generally designated by the referencenumeral 2?. It will be noted that there is provided a pair ofvertiinterconnecting the pressure-generating chamber 2! with theinterrupting chamber ll. Thus, liquid under pres sure from thepressure-generating chamber 2? may flow upwardly within the passages 23,as indicated by the arrows 29, into the interrupting chamber i i toeffect extinction of the interrupting arc l draw therein.

Suitable insulating plate structure is provided defining theinterrupting chamber i i which very effectively directs liquid intointimate engagement with the interrupting are !5. This insulating platestructure follows the teachings set forth in United States patentapplication filed December 22, 1945, Serial No. 636,940, now Patent No.2,467,760, April 19, 19%, by Leon R. Ludwig, Benjamin P. Baker, andWinthrop M. Leeds, and assigned'to the assignee of the instantapplication. Preferably, this plate structure consists of fibreinsulating piates of three different types. The first type, designatedby the reference character 3!, has portions removed therefrom to defineinlet passages 32, more clearly shown in Fig. 2. Adjacent each inletinsulating plate 3i is, aninsulating orifice plate 33 having an orifice34 provided therein through which passes the movable contact member 14during its opening motion.

On the other side of the orifice insulating plate 33 from the inletplate 3l'is a vent plate, generally designated by the reference numeral35. Preferably, the vent plate 35 is composite and consists of twoidentical halves 36 spaced laterally apart to provide a pair of opposedoutwardly extending vent passages 31, more clearly shown in Fig. 3.

From the foregoing description, it will be apparent that the oil passesinwardly toward the interrupting arc I5 through the opposed inletpassages 32, thence through the orifices 34 provided by the orificeplates 33 to exhaust outwardly away from the interrupting arc l5 out ofthe unit 6 through the opposed vent passages 31. Extinction of theinterrupting are it soon follows and the circuit is interrupted.

It will be noted that the lower end of the movable contact member llmakes electrical engagement with contact clips 38 and passes downwardlyinto an operating cylinder 3%. The operating cylinder 39 is threadedlyconnected at 49 to a cup-shaped metallic casting ii. The lower end ofthe operating cylinder 39 is closed by an apertured closure cap 22threadedly secured, as at 53, to the lower end of the operating cylinder39. Apertures 44 are provided adjacent the lower end of the operatingcylinder 39 so that the region below the operating piston 35 freelycommunicates with the region 55 which is substantially at atmosphericpressure. The operating piston d5 4 has a lost-motion connection withthe lower end 4'! of the movable contact member H. The lower end 4? ofthe movable contact member I! has an enlarged metallic cyindrical memberlla rigidly secured thereto having diagonal cuts 43 formed therein. Thecuts 43 cooperate with an inwardly extending flange portion 49 of theoperating piston to provide a valve means, generally designated by thereference numeral 58 which is closed during the downward opening motionof the operating piston :35 and movable contact member H. The valvemeans 50 closes during the opening operation by virtue of the fact thatthe flange portion 49 covers the tops of the cuts or recesses 48. Duringclosing the valve means 58 is open as later described.

A compression spring 52 is provided within the lower end of theoperating cylinder 39, having its lower end seated upon the closure cap42 and having its upper end bearing against an inwardly extending flangeportion 53 of the operating piston '65. Thus, during the closing upwardmotion of the movable contact member H, the spring 52' first raises theoperating piston :35 to open the valve means 58 and subsequently afterthe lost-' 'motion is taken up, strikes the cylindrical member 41a tocause thereby upward closing motion of the contact member ll, the valvemeans 50 being open during the entire closing operation since liquid canby pass the member 41a through the recesses 48.

My improved hydraulically operated mechanism 54 also includes a pumpingpiston 55 having an inwardly extending portion 56 which bears againstthe outer surface of the operating cylinder 39 being guided thereby. Abattery of compression springs 5? is provided to bias the pumping piston55 downwardly in the circuit opening direction to thereby compressliquid within the region 58. This liquid under pressure within theregion 58 may pass through apertures 59 pros" vided in the operatingcylinder 39 to act downwardly upon the operating piston 45 in the mannerpreviously described.

The pumping piston 55 has a depending cylindrical portion 60 which makesthreaded engagement, as at Bl, with an insulating tube 62, the lower endof which makes threaded engagement with a metallic bumper 63. The bumper63 is preferably threaded, as at 64, adjacent the lower end of theinsulating tube 52.

The bridging member I is composite, having an upper conducting portion65 and a lower insulating portion 65. The portion 65 has an upwardlyextending piece iii which passes between a pair of jaw-type stationarydisconnect fingers 63, biased toward each other by any suitable means,not shown. The disconnect fingers 6B are electrically connected by aconnector 59 to the lower metallic plate 19 of the unit 6.

I have provided a cylindrically-shaped follower member H which has aninwardly extending flange portion i2 at its upper end. The upper edge 3of the pumping piston 55 picks up the follower member 'H during theclosing stroke against the downward biasing action exerted by acompression spring i l. The upper end of the compression spring it bearsagainst the metallic casting M, and the lower end of the compressionspring 14 bears against a radially outwardly extending flange portion ofthe follower member I I.

To facilitate low current interruption when the pressure generatedwithin the pressure-generating chamber 21 by the pressure-generating arcnow be explained.

2511s relatively low, I have provided a separate independently movablepumping piston 7.6 which is picked up during the closing stroke by ashoulder portion 11 of the pumping piston 55. Arelatively lightcompression spring 18 retracts the pumping piston "56 in the closedposition, as shown in Fig. 2, forcing the upper end 19 thereof againststeps 89 integrally formed with the casting 4i Consequently, during theopening stroke there is a time-delay before the follower member H picksup the pumping piston 75 to force it downwardly by the action of thecompression spring 14. The reason for the delayed action of the pumpingpiston 75 during low current interruption is set forth and claimed inUnited States patent application filed December 15, 1943, Serial No. 514366, now abandoned, and continued in patent application Serial No.6,436, filed February 5, 1948, by Winthrop M. Leeds, Robert .E.Friedrich, .and Francis J. Fry and assigned to the assignee of theinstant application.

The downward opening movement of the pumping piston '15 is effective toforce oil outwardly through apertures 8| provided in the casting 4| andupwardly as indicated by the arrows 82 through a separate passage means,in this instance consisting 'of two vertically extending passages 83.

By the provision of the passages 83 separate from the passages 28, thereis no possibility of fluid within the passages 28 coming from thepressure-generating are 26 contaminating the fluid within the verticalpassages 83 moving upwardly from the auxiliary pumping piston 16.

Thus, clean oil is provided by action of the pumping piston 15.

I have provided venting means 84, 85 at opposite ends of the unit 5 toprovide a chimney-like venting arrangement, which venting means ishydraulically actuated at the extreme end of the opening operation. Thisresults since I have provided a cylinder 86 secured, as by welding at81, to the lower plate 19 of the unit 6. The cylinder 96 has apertures88 provided therein so that during the initial downward opening motionof the pumping piston 55 liquid will not be compressed within the region89. It is only near the end of the opening operation, after interruptionof the arcs has been completed, that the downward opening movement ofthe pumping piston 55 is effective to compress oil within the region 89and place the oil within the insulating tubes 95 under pressure. At thistime the oil under pressure within the tubes 95 forces the pistons 9|associated with the venting means 84, 85 to open the valves 92associated with the venting means 84, 85. Thus, at the extreme end ofthe opening operation contaminated fluid permitted to freely flow out.of the unit by the simultaneous opening of the venting means 84, 85 atopposite ends of the .unit 5.

In similar manner venting means 93 .is pro vided at the lower end of thepressure-generating chamber 2?, as shown in Fig. 3. This permits thepressure-generating chamber 2'! to be freely vented the extreme end or".the opening operation. The pistons 9! associated with the venting means93 are actuated by oil under pressure within tubes 24 which communicatewith the a region 89; Thus, all six of the pistons 9| are simultaneouslyactuated by the final downward opening travel or" the pumping piston 55.

The-operation of my improved interrupter will In the closed circuitposition of the interrupter, as shown in Fig. .2, the electrical circuittherethrough includes conducting contact foot 9, conducting plate it,.shunt =95. stationary contact is, movable contact 14, stationarycontacts 20, strap connectors 2i, stationary contacts l8, movablecontact member :17, contact .clips 33, casting 4], lower plate it,connectors 59, stationary disconnect fingers 68, upstanding conductingpiece 6'! of the bridging member I and through the right-handarcextinguishing unit 6 in like manner to the other terminal of theinterrupter.

When it is desired to open the electrical circuit passing through theinterrupter, suitable mechanism, not shown, which is responsive toeither manual operation or to the existence of excessive currentconditions in the circuit, causes downward opening motion of the liftrod 8. The downward movement of the insulating liftrod 8 causescorresponding downward opening movement of the composite bridging member1.

The downward movement of the bridging member I permits the battery or"compression springs 51 to force the pumping piston 55 downwardly tocompress oil within the region 53. This ,oil under pressure within theregion 58 passes through the apertures -52 provided in the operatingcylinder 3?). This oil then acts upon the top surface of the operatingpiston 55 to cause it to move downwardly against the biasing action 62erted by the compression spring 52. After the lost-motion between theoperating piston 45 and the movabfe contact member I? is taken up, thevalve means 59 is closed and the downward movement of the operatingpiston 45 carries the .movable contact H downwardly with it. Since theinsulating portion l6 interconnects the contacts 14, H, thepressure-generating are 26 and :the interrupting are [5 will besubstantially simultaneously established respectively within thepressure-generating chamber 21 and the interrupting chamber H.

Oil under pressure from the pressure-generating are 26 flows upwardlyduring high current interruption through the passages '28 to effectextinction of the interrupting are 15 within the interrupting chamber i!in a manner as previously described. During this high currentinterruption the auxiliary piston 76 is not effective and is merelystalled by the high pressure existing within the unit. One or more tubes24 provide substantially atmospheric pressure in the region 25 in backof the pistons 55,, "it so that the biasing action exerted by spring 74is overcome by the high pressure existing within the unit. It is onlyduring low current interruption when the pressure within "thepressure-generating chamber 2? is low that the auxiliary pumping pistonit is effective to force oil upwardly through the passages 83 and intothe interrupting chamber I i to effect the extinction of theinterruptingarc Hi established therein.

It will be noted that the areas of the pumping piston 55 and theoperating piston is are such as to cause considerable travel ofthecontact structure for a much shorter travel of the the pumping piston55. This gives high speed opening essential for three cycle performance.It will also be noted that the path between the two pistons 55, 35 isshort to reduce to a mini mum hydraulic friction losses.

The pumping piston 55 continues to move downwardly under the action ofthe compression springs 5'! as permitted by downward motion of theinsulating portion IE6 of the bridging member 1. Finally, followinginterruption of the arcs, the conducting piece 51, or the movabledisconnect contact, separates from the stationary disconnect fingers 68to insert two isolating. gaps in the circuit, as more clearly shown bythe dotted lines 95 of Fig. 1.

It will therefore be apparent that the circuit is broken within the unit6 and not at the disconnect contacts 61, 68, the latter separating onlyfollowing circuit interruption. It will be ob served that followinginterrupting of the arcs i5,

29 the pumping piston 55 establishes oil pressure within the regions 89to effect opening of the venting means 84, 85 at opposite ends of theunit to thereby permit contaminated fluid to freely flow out of the unit6 by the chimneylike vent passages formed. Also as shown in Fig. 3. theventing means 93 will be opened to permit venting of thepressure-generating chamber 27.

Finally, the downward movement of the pumping piston 55 is halted by itsstriking th portion 91, and the compression spring 52 at this timeeffects reclosure of the contact structure. In other words, thecompression spring 52 first forces the operating piston 45 upwardly tofirst open the valve means 59 permitting leakage of oil around the lowerend 4'! of the movable contact member 11.

After the lost-motion is taken up and the valve means 59 is open, theoperating piston 45 picks up the movable contact member 11, forcing thelatter upwardly to thereby effect re-engagement of the contacts ll, l8,l4, 13. Hence the electrical circuit is completed through theinterrupter in the fully open circuit position thereof, the isolatinggaps withstanding the impressed voltage.

During the interruption of low currents, as previously mentioned, thedownward movement of the follower member 1 I, as caused by the bias" ingaction of the compression spring 14, picks up the auxiliary piston 16 toforce fluid up through the passages 83 and toward the interrupting are[5.

A flap valve 98 is provided which closes the region 58 during theopening operation and permits oil to enter the region 58 through holes99 during the closing stroke.

During the closing operation of the interrupter,

suitable means causes upward closing motion of the lift rod 8. Thisraises the bridging member l and first causes engagement between thebumper 53 and the insulation portion 68 of bridg ing member 1. Thus,even before the disconnect contacts 81, 68 are engaged, the bumper 63has been moved upwardly a considerable distance to thereby effectcharging of the pumping piston 55. The reason for this is that ifexcessive current conditions still exist in the circuit during theclosing operation and prestriking occurs between contacts 91, 58 tothereby reverse the motion of. the operating mechanism, the pumpingpiston 55- will have been sufficiently charged at this time of reversalto effect opening of the contact structure in the manner previouslydescribed. In other words, if the pumping piston 55 were not partlycharged by the time the contacts 67, 68 were sufficiently close togetherto be conductively bridged by prestriking, the pumping piston 55 wouldbe ineffective to open the contact structure and the interrupter wouldfail. By partly charging the pumping piston- 55 before there is apossibility of flashover between the disconnect contacts 51, 63,assurance is had that'the breaker will operate in the nor mal mannershould reversal of the mechanism take place at an intermediate pointin-the closing operation.' v

From the foregoing, it will be apparent that during the closingoperation the actuating member 66 causes upward charging movement of thepumping piston 55 to thereby cause opening of the flap. valve 98 to drawoil through the apertures 99 into the region 58. Also the shoulderportion 11 of pumping piston 55 picks up the auxiliary piston 75.Further, the upper edge 13 of pumping piston 55 picks up the followermember H and effects the charging motion thereof.

During the initial downward movement of the pumping piston 55, thecompression spring 18 maintains the auxiliary pumping piston 16 againstthe stops so that there is a predetermined time interval before thepiston 76 is effective to pump oil.

From the foregoing, it will be apparent that m improved interrupter isparticularly applicable for high speed reclosing operations due to theprovision of the venting means 84, and 93. Thus, the gases which tend tocontaminate the oil within the unit 6 are rapidly expelled therefromfollowing extinction of the arcs. To check the contact structure duringinstallation of the interrupter, it is necessary only to thread a longstud, not shown, into the tapped hole H39 and move the two contacts 14,H and the insulating portion l6 vertically. The interrupter is easilyinstalled requiring only that the bridging member I be sufficientlyaligned to cause the conducting portion 67 thereof to pass between thedisconnect fingers 88, and that the piston 55 is sufiiciently chargedbefore engagement of the disconnect contacts. Neither of thesedimensions is very critical.

Certain features of the contact structure in volving the contacts l4, lltied together by the insulating rod l6,,together with the inverted orderofithe pressure-generating chamber and the interrupter chamber, are setforth and claimed in United States patent application filed February 21,1947, Serial No. 729,934 by Robert E. Friedrich and Winthrop M. Leeds.Features involving the hydraulic operating mechanism 54 are, in part,covered by United States patent application filed October 30, 1946,Serial No. 706,735, now Patent No. 2,463,029, March 1, 1949, by FrancisJ. Fry. A further feature involving the part charging of the pumpingpiston 55 during the closing stroke before engagement of the disconnectfingers 6'1, 68 is described and claimed in United States patentapplication filed April 4, 1947, Serial No. 739,273 by Winthrop M.Leeds. The feature of broadly providing a chimney effect is describedand claimed in United States patent application filed November 21, 1946,Serial No. 711,422, now Patent No.'2,465,218, March 22, 1949, by RobertE. Friedrich. All of the foregoing applications are assigned to theassignee of the instant application.

Although I have shown and described a specific structure, it is to beclearly understood that the same was merely for the purpose ofillustration and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the appended claims.

I claim as my invention:

'1. A circuit interrupter having contact means operable to establish anare including a movable contact, an operating piston for actuating themovable contact, an operatin cylinder within which the operating pistonmoves, a movable pump piston surrounding the operating cylinder andhaving the region of compression immediately adjacent the externalsurface of the operating cylinder, and apertures through the operatingcylinder so that the travel of fluid between the two pistons will beshort to minimize hydraulic friction losses.

2. A circuit interrupter having contact means operable to establish anare including a movable contact, an operating piston for actuating themovable contact, an operating cylinder Within which the operating pistonmoves, a movable pump piston surrounding the operating cylinder andhaving the region of compression immediately adjacent the externalsurface of the operating cylinder, apertures through the operatingcylinder so that the travel of fluid between the two pistons will beshort to minimize hydraulic friction losses, means biasing the movablecontact toward its closed position, and valve means associated with theoperating piston to permit fluid leakage around the operating pistonduring the closing movement of the movable contact.

3. A circuit interrupter including a pair of arcextinguishing units,each unit having contact means operable to establish an are including amovable contact, an operating piston for actuating the movable contact,an operating cylinder within which the operating piston moves, a movablepump piston surrounding the operating cylinder and having the region ofcompression im mediately adjacent the external surface of the operatingcylinder, apertures through the operating cylinder so that the travel offluid be-- tween the two pistons will be short to minimize hydraulicfriction losses, and a movable bridging member electrically connectingthe two units in series in the closed circuit position and charging thetwo movable pump pistons associated with the two units.

4. A liquid break arc-extinguishing unit having contact means includinga movable contact member separable to establish an arc, a hydraulicoperating mechanism for the movable contact member including anoperating piston operatively connected with the movable contact member,an operating cylinder within which the operating piston moves, a movablepumping piston for forcing liquid into the operating cylinder to effectthereby opening motion of the operating piston and movable contactmember, means biasing the pumping piston in a direction to separate thecontact means, an actuating member to charge the pumping piston duringthe closing operation of the unit against said biasing means, andanother pumping piston operatively related to the pumping piston toassist in low current interruption.

5. A liquid break arc-extinguishing unit having contact means includinga movable contact member separable to establish an arc, a hydraulicoperating mechanism for the movable contact member including anoperating piston operatively connected with the movable contact member,an operating cylinder within which the operating piston moves, a movablepumping piston for forcing liquid into the operating cylinder to effectthereby opening motion of the operating piston and movable contactmember, means biasing the pumping piston in a direction to separate thecontact means, an actuating member to charge the pumping piston duringthe closing operation of the unit against said biasing means, a followermember, means biasing the follower member in said direction, and adelayed acting piston picked up after a predetermined travel of thefollower member to assist in low current interruption.

6. Aliquid break arc-extinguishing unit having contact means including amovable contact member separable to establish an arc, a hydraulicoperating mechanism for the movable contact member including anoperating piston operatively connected with the movable contact memher,an operating cylinder within which the operating piston moves, a movablepumping piston for forcing liquid into the operating cylinder to effectthereby opening motion of the operating piston and movable contactmember, means biasing the pumping piston in a direction to separate thecontact means, an actuating member to charge the pumping piston duringthe closing operation of the unit against said biasing means, ventingmeans for the arc-extinguishing unit, and means whereby the pumpingpiston opens the venting means near the end of its opening motion insaid direction to vent the unit.

ROBERT E. FRIEDRICH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,102,768 Trencham et al. Dec.21, 1937 2,147,497 Prince et al. Feb. 14, 1939 2,239,554 Duffing Apr.22, 1941 2,258,226 Skeats Oct. 7, 1941 2,386,611 Ileman Oct. 9, 19452,420,889 Leeds May 20, 1947 2,422,569 Leeds June 17, 1947 2,465,218Friedrich Mar. 22, 1949 2,477,788 Cumming Aug. 2, 1949

